Release v2.0.0 semantic reliability

[docxology]

Summary

• Release v2.0.0 as the semantic fidelity and cross-framework reliability release.
• Add strict semantic parse/JSON round-trip contracts for maintained model families.
• Add cross-framework reliability ledgers with profiled backend compatibility and a real GridWorld PyMDP/RxInfer/ActiveInference.jl comparison.
• Update roadmap, docs, version metadata, uv lock, and capability-contract guards.

Validation

• uv run --extra dev python -m pytest src/tests/gnn src/tests/export src/tests/pipeline src/tests/analysis src/tests/report -q -> 764 passed
• uv run --extra dev python scripts/run_semantic_fidelity_gate.py --manifest input/model_family_manifest.json --output-dir /tmp/gnn-semantic-fidelity --strict -> passed
• uv run --extra dev python scripts/run_cross_framework_reliability.py --manifest input/model_family_manifest.json --output-dir /tmp/gnn-cross-framework --strict -> passed
• uv run --extra dev python scripts/run_model_family_acceptance.py --manifest input/model_family_manifest.json --output-dir /tmp/gnn-family-acceptance-all --strict -> passed
• git diff --check -> passed
• ruff check/format-check over changed Python -> passed
• docs audit, GNN doc patterns, maintained-doc terms, repo terminology, capability contracts -> passed
• pytest collect-only with Ollama integration files ignored -> 2411 collected
• full suite with Ollama integration files ignored -> 2393 passed, 17 skipped, 1 xfailed
• tracked output/ restored and clean